Abstract

High-energy electron scattering is used to investigate Tafilmsimplanted with 10 keV O ions. These films are of interest as they have been used for the fabrication of memristors. High-energy electron scattering is used with incoming electron energies ranging from 5 to 40 keV. The inelastic mean free path, and hence the probing depth, is at these energies of the same order as the range of the implanted ions. At the same time, we can distinguish the mass of the atom that scattered the electron elastically, due to the dependence of the recoil energy on the mass of the scatterer. This allows us to determine quantitatively the atomic composition near the surface from the signal of electrons that have scattered elastically but not inelastically. Electrons that have scattered inelastically as well as elastically provide us with information on the possible electronic excitations. Their signal is used to monitor the presence of the Ta2O5 phase near the surface (characterised by a significant band gap of ), and estimate at what depth below the surface pure Ta metal is present. In this way, we obtain a fairly detailed picture of the elemental composition and electronic properties of these films.

Received 22 June 2013Accepted 31 July 2013Published online 20 August 2013

Acknowledgments:

This research was made possible by funding of the Australian Research Council. Oxygen-implanted Tantalum films were provided by Dr. S. Ruffell and Dr. J. England of Varian Semiconductor Equipment, a Division of Applied Materials, as part of a broader collaboration funded by an Australian Research Council Linkage Project Grant. The stay of P.L.G. at the ANU was made possible by a Grant No. 10209/12-3 from CAPES (Brazil). S.K.N. gratefully acknowledges RSAA for his Ph.D. scholarship.